Question about serif / sans serif combinations

I'm using Linotype Didot (or an extremely similar custom face) for an identity system and I'm contemplating over whether or not to use a sans serif for body copy (for collateral pieces, etc). I'm going for high end/modern simplicity. Do you all have any recommendations? I have come to the conclusion that using another serif face would be overkill, but I am open to suggestions.

The usual suspect following the internal structure of a didone type would be Helvetica. But this is not the best type for body copy.
You could try Walbaum however, also didone, comfortable to read with a rather large x-height.